The invention relates to a sprinkler or a spray head comprising a housing, an inlet, a nozzle mounted in the housing, a passage from the inlet to the nozzle, and a holder for a release means, the holder being mounted in front of the nozzle so that it prevents the nozzle from spraying extinguishing medium forward without hindrance, the nozzle being arranged to spray extinguishing medium once the release means has been released, the holder being mounted in the housing by means of a locking mechanism, which is arranged to open and release the holder from the housing once the release means has been released.
The problem in the sprinklers of the above type is that the holder or some other part of the sprinkler always operates as an extinguishing-medium distributor, thus resisting the jet of extinguishing medium. Yet it is often desired that the nozzle can spray extinguishing medium without hindrance once the sprinkler has been released. If the extinguishing medium is water mist and the water mist hits the holder, the jet of extinguishing medium loses speed and momentum as the droplets gain in size. This is usually a drawback, since the aim is to spray water mist with a very small droplet size and, according to modern fire fighting technology, with high momentum and penetration capacity. Such an extinguishing medium absorbs heat very efficiently, and is simultaneously able to penetrate into the seat of fire. The longer the distance between sprinklers in a sprinkler system, the more important it is that individual sprinklers can spray directly forward, i.e. downward; otherwise a seat of fire directly under a sprinkler may expand, whereby the fire becomes more difficult to extinguish.
U.S. Pat. No. 4,618,002 discloses a sprinkler with such a design and structure that it can be embedded in the ceiling in an aesthetically pleasing manner. The sprinkler comprises a holder with a locking mechanism that opens in connection with the release as the release means melts. The locking mechanism comprises a spring, whose operation is crucial to the operation of the sprinkler. Whether or not the mechanism operates can be considered uncertain as the sprinkler has been unused for years, and, for example, the locking mechanism has dirtied and corrosion may have hampered the properties and operation of the spring. The sprinkler comprises a deflector, which prevents the extinguishing medium from being sprayed directly forward without hindrance when the sprinkler has been released.
U.S. Pat. No. 5,257,827 discloses a sprinkler comprising a valve that opens in connection with the release so as to direct the jet of extinguishing medium to the side. In this previously known sprinkler, the jet of extinguishing medium cannot be sprayed directly forward without hindrance.
U.S. Pat. No. 4,664,198 discloses a sprinkler with a locking mechanism that opens in connection with the release. A deflector prevents the extinguishing medium from being sprayed forcefully directly forward when the sprinkler is released.